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This paper describes a doctoral research in three areas: Hybrid ASP - an extension of Answer Set Programming for reasoning about dynamical systems, an extension of Set Constraint atoms for reasoning about preferences, computing stable models of logic programs using Metropolis type algorithms. The paper discusses a possible application of...

The focus of this paper lies on provably correct static analysis of logic programs, in particular on determinacy inference for logic programs containing cut, and on verified implementations thereof. For reasons which hardly need spelling out here, the question of whether a goal is deterministic or not is central in...

This paper investigates a type of logic programming language called "Axiomatic language". Axiomatic language is intended as a specification language where the user defines the external behavior of a program without giving an algorithm. The language implementation has the task of transforming this input specification into an equivalent efficient algorithm....

Description Logics are used more and more frequently for knowledge representation, creating an increasing demand for efficient automated DL reasoning. However, the existing implementations are inefficient in the presence of large amounts of data. This paper summarizes the results in transforming DL axioms to a set of function-free clauses of...

In this paper a general framework (based on soft constraints) to model and solve the fair allocation problem is proposed. The authors' formal approach allows to model different allocation problems, ranging from goods and resources allocation to task and chore division. Soft constraints are employed to find a fair solution...

Early validation of requirements is crucial for the rigorous development of software. Without it, even the most formal of the methodologies will produce the wrong outcome. One successful approach, popularised by some of the so-called lightweight formal methods, consists in generating (finite, small) models of the specifications. Another possibility is...

The authors present a novel counterexample generator for the interactive theorem prover Isabelle based on a compiler that synthesizes test data generators for functional programming languages (e.g., Standard ML, OCaml) from specifications in Isabelle. In contrast to naive type-based test data generators, the smart generators take the preconditions into account...

The paper presents a system for knowledge representation and coordination, where autonomous agents reason and act in a shared environment. Agents autonomously pursue individual goals, but can interact through a shared knowledge repository. In the authors' interactions, agents deal with problems of synchronization and concurrency, and have to realize coordination...

The CDAOStore is a portal aimed at facilitating the storage and retrieval of data and metadata associated to studies in the field of evolutionary biology and phylogenetic analysis. The novelty of CDAOStore lies in the use of a semantic-based approach to the storage and querying of data. This enables CDAOStore...

Probabilistic models that associate annotations to sequential data are widely used in computational biology and a range of other applications. Models integrating with logic programs provide, furthermore, for sophistication and generality, at the cost of potentially very high computational complexity. A methodology is proposed for modularization of such models into...

The authors elaborate upon new strategies and heuristics for solving multi-criteria optimization problems via Answer Set Programming (ASP). In particular, they conceive a new solving algorithm, based on conflict-driven learning, allowing for non-uniform descents during optimization. They apply these techniques to solve realistic Linux package configuration problems. To this end,...

RDF/S ontologies are often used in e-science to express domain knowledge regarding the respective field of investigation (e.g., cultural informatics, bioinformatics etc). Such ontologies need to change often to reflect the latest scientific understanding on the domain at hand, and are usually associated with constraints expressed using various declarative formalisms...

The authors describe an application of Prolog: a type checking tool for the Q functional language. Q is a terse vector processing language, a descendant of APL, which is getting more and more popular, especially in financial applications. Q is a dynamically typed language, much like Prolog. Extending Q with...

Today, Prolog is often used to solve well-defined, domain-specific problems that are part of larger applications. In such cases, a tight integration of the Prolog program and the rest of the application, which is commonly written in a different language, is necessary. One common approach is to compile the Prolog...

Privacy on the Internet is becoming a concern as an already significant and ever growing part of the daily activities is carried out online. While cryptography can be used to protect the integrity and confidentiality of contents of communication, everyone along the route on which a packet is traveling can...

Trustworthy applications in fully decentralized systems require a trust anchor. This paper describes how such an anchor can be implemented efficiently in p2p systems. The basic concept is to use threshold cryptography in order to sign messages by a quorum of peers. The focus is put on advanced mechanisms to...

Correctness problems in the iBGP routing, the de-facto standard to spread global routing information in Autonomous Systems, are a well-known issue. Configurations may route cost-suboptimal, inconsistent, or even behave non-convergent and -deterministic. However, even if a lot of studies have shown many exemplary problematic configurations, the exact scope of the...

Service-orientation provides concepts and tools for flexible composition and management of large-scale distributed software applications. The automated run-time management of such loosely coupled software systems, however, poses still major challenges and is therefore an active research area, including the use of novel computing paradigms. In this context, the dynamic and...

The paradigm of service-orientation promises a significant ease of use in creating and managing distributed software systems. A very important aspect here is that also application domain experts and stakeholders, who are not necessarily skilled in computer programming, get a chance to create, analyze, and adapt distributed applications. However, up...

The authors study distributed adaptive beamforming in networks of wireless nodes. In particular, they observe that for the synchronisation of carrier phases, distinct algorithmic configurations are optimal in various environmental settings and propose a protocol that utilises organic computing principles to find optimum parameters. Furthermore, they study the impact of...

Generating synthetic loads which are sufficiently close to reality represents an important and challenging task in performance and Quality-of-Service (QoS) evaluations of computer networks and distributed systems. Here, the load to be generated represents sequences of requests at a well-defined service interface within a network node. The paper presents a...

This paper presents an improved variant of the authors' Markov-based TCP traffic classifier and demonstrates its performance using traffic captured in a university network. Payload length, flow direction, and position of the first data packets of a TCP connection are reflected in the states of the Markov models. In addition,...

The usage of link quality based routing metrics significantly improves the quality of the chosen paths and by that the performance of the network. But, attackers may try to exploit link qualities for their purposes. Especially in tactical multi-hop networks, routing may fall prey to an attacker. Such routing attacks...

This paper presents an approach for ontology-based IT management based on a heavyweight (formal) ontology using the Web Ontology Language (OWL). The ontology comprises a complete OWL representation of the Common Information Model (CIM) and management rules defined in the Semantic Web Rule Language (SWRL). The ontology not only models...

This paper presents a new approach to exclude problems arising from dynamically switching between protected concurrent and unprotected single-threaded use of shared data when using software transactional memory in OO languages such as Java. The approach is based on a simple but effective programming model separating transactions from non-transactional operation....

Despite of all progress in terms of computational power, communication bandwidth, and feature richness, limited battery capacity is the major bottleneck for using the resources of mobile devices in innovative distributed applications. Incentives are required for motivating a user to spend energy on behalf of other users and it must...

In this paper, the authors present a novel peer-to-peer system specifically designed to support the unique properties of traffic information systems. They discuss important design decisions, such as update strategies and algorithms for dynamic vehicular route planning. The system is then assessed using a combination of network (OverSim/OMNeT++) and road...

Measuring the per-flow traffic in large networks is very challenging due to the high performance requirements on the one hand, and due to the necessity to merge locally recorded data from multiple routers in order to obtain network-wide statistics on the other hand. The latter is nontrivial because traffic that...

The problem of localizing nodes without GPS based on a small fraction of anchor nodes which are aware of their positions is considered to be an important service for applications in wireless ad hoc networks. With an adversary trying to mislead nodes about their estimated locations, several approaches aiming to...

Intrusion Detection Systems (IDS) offer valuable measures to cope with today's attacks on computers and networks. But the increasing performance of networks and end systems and the growing complexity of IT systems lead to rapidly growing volumes of observation data and large signature bases. Therefore, IDS are forced to drop...

Hop-count based weighted centroid localization is a simple and straightforward localization algorithm, which uses anchors with known positions and the hop count to these anchors to estimate the real position of nodes. Especially in sensor networks, where energy restrictions prevent more complex algorithms, this fast and simple algorithm can be...

This paper introduces an architectural approach to access the Web via a virtual Web browser executed within a secure Cloud environment. The Web has become an indispensable prerequisite of everyday live and the Web browser is the most used application on a variety of distinct devices. The content delivered by...

The present paper presents a model driven generative approach to the design and implementation of distributed business applications, which consequently and systematically implements many years of MDSD experience for the software engineering of large application development projects in an industrial context. MDSD (Model-Driven Software Development) is a generic term covering...

Communication is crucial to the coordination and efficient operation of public transport systems. However, deployment of infrastructure based communication systems is expensive, esp. due to long-term operational costs. Delay tolerant vehicular networks are a promising alternative since only very few infrastructure elements are required. This paper presents a DTN routing...

The development of the Information-Centric Networking (ICN) concept is one of the significant results of different international Future Internet research activities. In this concept, the principal paradigm is not end-to-end communication between hosts - as in the current Internet architecture. Instead, an increasing demand for highly scalable and efficient distribution...

The use of randomization in concurrent or distributed systems is often key to achieving certain objectives - it is used in distributed algorithms to break symmetry and in cryptographic protocols to achieve semantic security. The formal analysis of such systems has often modelled them as Markov Decision Processes, that has...

The authors consider the problem of model checking message-passing systems with real-time requirements. As behavioural specifications, they use Message Sequence Charts (MSCs) annotated with timing constraints. Their system model is a network of communicating finite state machines with local clocks, whose global behaviour can be regarded as a timed automaton....

The authors study (collapsible) higher-order pushdown systems - theoretically robust and well-studied models of higher-order programs - along with their natural subclass called (collapsible) higher-order basic process algebras. They provide a comprehensive analysis of the model checking complexity of a range of both branching-time and linear-time temporal logics. They obtain...

Quantitative properties of timed regular languages, such as information content (growth rate, entropy) are explored. The approach suggested by the same authors is extended to languages of timed automata with punctual (equalities) and non-punctual (non-equalities) transition guards. Two size measures for such languages are identified: mean dimension and volumetric entropy....

The development of the Information-Centric Networking (ICN) concept is one of the significant results of different international Future Internet research activities. In this concept, the principal paradigm is not end-to-end communication between hosts - as in the current Internet architecture. Instead, an increasing demand for highly scalable and efficient distribution...

Service-orientation provides concepts and tools for flexible composition and management of large-scale distributed software applications. The automated run-time management of such loosely coupled software systems, however, poses still major challenges and is therefore an active research area, including the use of novel computing paradigms. In this context, the dynamic and...

The paradigm of service-orientation promises a significant ease of use in creating and managing distributed software systems. A very important aspect here is that also application domain experts and stakeholders, who are not necessarily skilled in computer programming, get a chance to create, analyze, and adapt distributed applications. However, up...

The authors study distributed adaptive beamforming in networks of wireless nodes. In particular, they observe that for the synchronisation of carrier phases, distinct algorithmic configurations are optimal in various environmental settings and propose a protocol that utilises organic computing principles to find optimum parameters. Furthermore, they study the impact of...

Generating synthetic loads which are sufficiently close to reality represents an important and challenging task in performance and Quality-of-Service (QoS) evaluations of computer networks and distributed systems. Here, the load to be generated represents sequences of requests at a well-defined service interface within a network node. The paper presents a...

This paper presents an improved variant of the authors' Markov-based TCP traffic classifier and demonstrates its performance using traffic captured in a university network. Payload length, flow direction, and position of the first data packets of a TCP connection are reflected in the states of the Markov models. In addition,...

The usage of link quality based routing metrics significantly improves the quality of the chosen paths and by that the performance of the network. But, attackers may try to exploit link qualities for their purposes. Especially in tactical multi-hop networks, routing may fall prey to an attacker. Such routing attacks...

This paper presents an approach for ontology-based IT management based on a heavyweight (formal) ontology using the Web Ontology Language (OWL). The ontology comprises a complete OWL representation of the Common Information Model (CIM) and management rules defined in the Semantic Web Rule Language (SWRL). The ontology not only models...

This paper presents a new approach to exclude problems arising from dynamically switching between protected concurrent and unprotected single-threaded use of shared data when using software transactional memory in OO languages such as Java. The approach is based on a simple but effective programming model separating transactions from non-transactional operation....

Despite of all progress in terms of computational power, communication bandwidth, and feature richness, limited battery capacity is the major bottleneck for using the resources of mobile devices in innovative distributed applications. Incentives are required for motivating a user to spend energy on behalf of other users and it must...

In this paper, the authors present a novel peer-to-peer system specifically designed to support the unique properties of traffic information systems. They discuss important design decisions, such as update strategies and algorithms for dynamic vehicular route planning. The system is then assessed using a combination of network (OverSim/OMNeT++) and road...

Measuring the per-flow traffic in large networks is very challenging due to the high performance requirements on the one hand, and due to the necessity to merge locally recorded data from multiple routers in order to obtain network-wide statistics on the other hand. The latter is nontrivial because traffic that...

The problem of localizing nodes without GPS based on a small fraction of anchor nodes which are aware of their positions is considered to be an important service for applications in wireless ad hoc networks. With an adversary trying to mislead nodes about their estimated locations, several approaches aiming to...

Intrusion Detection Systems (IDS) offer valuable measures to cope with today's attacks on computers and networks. But the increasing performance of networks and end systems and the growing complexity of IT systems lead to rapidly growing volumes of observation data and large signature bases. Therefore, IDS are forced to drop...

Hop-count based weighted centroid localization is a simple and straightforward localization algorithm, which uses anchors with known positions and the hop count to these anchors to estimate the real position of nodes. Especially in sensor networks, where energy restrictions prevent more complex algorithms, this fast and simple algorithm can be...

This paper introduces an architectural approach to access the Web via a virtual Web browser executed within a secure Cloud environment. The Web has become an indispensable prerequisite of everyday live and the Web browser is the most used application on a variety of distinct devices. The content delivered by...

The present paper presents a model driven generative approach to the design and implementation of distributed business applications, which consequently and systematically implements many years of MDSD experience for the software engineering of large application development projects in an industrial context. MDSD (Model-Driven Software Development) is a generic term covering...

Privacy on the Internet is becoming a concern as an already significant and ever growing part of the daily activities is carried out online. While cryptography can be used to protect the integrity and confidentiality of contents of communication, everyone along the route on which a packet is traveling can...

Communication is crucial to the coordination and efficient operation of public transport systems. However, deployment of infrastructure based communication systems is expensive, esp. due to long-term operational costs. Delay tolerant vehicular networks are a promising alternative since only very few infrastructure elements are required. This paper presents a DTN routing...

Trustworthy applications in fully decentralized systems require a trust anchor. This paper describes how such an anchor can be implemented efficiently in p2p systems. The basic concept is to use threshold cryptography in order to sign messages by a quorum of peers. The focus is put on advanced mechanisms to...

The authors elaborate upon new strategies and heuristics for solving multi-criteria optimization problems via Answer Set Programming (ASP). In particular, they conceive a new solving algorithm, based on conflict-driven learning, allowing for non-uniform descents during optimization. They apply these techniques to solve realistic Linux package configuration problems. To this end,...

RDF/S ontologies are often used in e-science to express domain knowledge regarding the respective field of investigation (e.g., cultural informatics, bioinformatics etc). Such ontologies need to change often to reflect the latest scientific understanding on the domain at hand, and are usually associated with constraints expressed using various declarative formalisms...

The authors describe an application of Prolog: a type checking tool for the Q functional language. Q is a terse vector processing language, a descendant of APL, which is getting more and more popular, especially in financial applications. Q is a dynamically typed language, much like Prolog. Extending Q with...

Today, Prolog is often used to solve well-defined, domain-specific problems that are part of larger applications. In such cases, a tight integration of the Prolog program and the rest of the application, which is commonly written in a different language, is necessary. One common approach is to compile the Prolog...

Early validation of requirements is crucial for the rigorous development of software. Without it, even the most formal of the methodologies will produce the wrong outcome. One successful approach, popularised by some of the so-called lightweight formal methods, consists in generating (finite, small) models of the specifications. Another possibility is...

The authors present a novel counterexample generator for the interactive theorem prover Isabelle based on a compiler that synthesizes test data generators for functional programming languages (e.g., Standard ML, OCaml) from specifications in Isabelle. In contrast to naive type-based test data generators, the smart generators take the preconditions into account...

The paper presents a system for knowledge representation and coordination, where autonomous agents reason and act in a shared environment. Agents autonomously pursue individual goals, but can interact through a shared knowledge repository. In the authors' interactions, agents deal with problems of synchronization and concurrency, and have to realize coordination...

The CDAOStore is a portal aimed at facilitating the storage and retrieval of data and metadata associated to studies in the field of evolutionary biology and phylogenetic analysis. The novelty of CDAOStore lies in the use of a semantic-based approach to the storage and querying of data. This enables CDAOStore...

Probabilistic models that associate annotations to sequential data are widely used in computational biology and a range of other applications. Models integrating with logic programs provide, furthermore, for sophistication and generality, at the cost of potentially very high computational complexity. A methodology is proposed for modularization of such models into...

This paper describes a doctoral research in three areas: Hybrid ASP - an extension of Answer Set Programming for reasoning about dynamical systems, an extension of Set Constraint atoms for reasoning about preferences, computing stable models of logic programs using Metropolis type algorithms. The paper discusses a possible application of...

In this paper a general framework (based on soft constraints) to model and solve the fair allocation problem is proposed. The authors' formal approach allows to model different allocation problems, ranging from goods and resources allocation to task and chore division. Soft constraints are employed to find a fair solution...

The focus of this paper lies on provably correct static analysis of logic programs, in particular on determinacy inference for logic programs containing cut, and on verified implementations thereof. For reasons which hardly need spelling out here, the question of whether a goal is deterministic or not is central in...

This paper investigates a type of logic programming language called "Axiomatic language". Axiomatic language is intended as a specification language where the user defines the external behavior of a program without giving an algorithm. The language implementation has the task of transforming this input specification into an equivalent efficient algorithm....

Description Logics are used more and more frequently for knowledge representation, creating an increasing demand for efficient automated DL reasoning. However, the existing implementations are inefficient in the presence of large amounts of data. This paper summarizes the results in transforming DL axioms to a set of function-free clauses of...

The authors consider the problem of model checking message-passing systems with real-time requirements. As behavioural specifications, they use Message Sequence Charts (MSCs) annotated with timing constraints. Their system model is a network of communicating finite state machines with local clocks, whose global behaviour can be regarded as a timed automaton....

The authors study (collapsible) higher-order pushdown systems - theoretically robust and well-studied models of higher-order programs - along with their natural subclass called (collapsible) higher-order basic process algebras. They provide a comprehensive analysis of the model checking complexity of a range of both branching-time and linear-time temporal logics. They obtain...

Quantitative properties of timed regular languages, such as information content (growth rate, entropy) are explored. The approach suggested by the same authors is extended to languages of timed automata with punctual (equalities) and non-punctual (non-equalities) transition guards. Two size measures for such languages are identified: mean dimension and volumetric entropy....

The use of randomization in concurrent or distributed systems is often key to achieving certain objectives - it is used in distributed algorithms to break symmetry and in cryptographic protocols to achieve semantic security. The formal analysis of such systems has often modelled them as Markov Decision Processes, that has...

This paper considers a tree-rewriting framework for modeling documents evolving through service calls. The authors focus on the automatic verification of properties of documents that may contain data from an infinite domain. Their establish the boundaries of decidability: while verifying documents with recursive calls is undecidable, they obtain decidability as...

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